Compact DUV reflective Fourier ptychographic microscopy for high-throughput surface measurements

Area of Science:

• Optics and Photonics
• Surface Metrology
• Microscopy

Background:

• High-throughput surface measurements are vital for applications like optical components and VLSI circuits.
• Reflective Fourier ptychographic microscopy (RFPM) offers high-resolution imaging for reflective surfaces.
• Existing RFPM methods often involve bulky illumination systems and complex calibration.

Purpose of the Study:

• To develop a novel, simpler, and more compact deep ultraviolet (DUV) RFPM system.
• To overcome the limitations of previous RFPM illumination and calibration requirements.
• To demonstrate the capability of DUV RFPM for nanometer-scale height profiling.

Main Methods:

• Implementation of a DUV RFPM system utilizing a single LED matrix as the illumination source.
• Employing a 5×, 0.12 numerical aperture (NA) DUV objective lens.
• Demonstration of the experimental setup with wafer standards and a machined concave mirror.

Main Results:

• Achieved a 1.6 mm field of view and 690 nm spatial resolution.
• Enabled nanometer-scale height profiling of reflective surfaces.
• Demonstrated a significantly simpler and more compact RFPM setup compared to prior art.

Conclusions:

• The novel DUV RFPM method provides a more accessible and efficient approach to high-resolution surface inspection.
• The single LED matrix illumination simplifies the system's design and calibration.
• This technique holds promise for various applications requiring precise reflective surface metrology.